Thank you very much for taking the time to answer these questions. Tory Bruno has stated that the SMART Reuse system won't be used on the Vulcan initially, but will be phased in. How long do you think it will take for them to start using it? And do you believe it will be done gradually, alla SpaceX or will it be much more rapid, say one or two experimental launches, then going full engine reuse?

Cheers,

I expect we will phase it in gradually. The first step is to mature the HIAD (hypersonic inflatable aerodynamic decelerator) technology. We are working with NASA on that.

Dr. Sowers, thank you again for coming back to answer more questions about your new rocket. I can't wait to watch it come together over the next few years, and hope Blue Origin can be persuaded to release engine testing videos.

If I recall correctly, ACES was a modular family that would fly with varying numbers of engines and even varying sizes of tanks to accomodate different mission requirements. Is that still the plan for the future Vulcan upper stage?

Thank you again. Go Vulcan! Go Centaur!

We've been working ACES for many years. I'm really excited that we finally have a firm plan to implement it. The architectural details are still being worked out. The configuration(s) will depend in part on the engine selection we'll make in the next couple of years. The architecture based on a BE-3U will be different from that based on an RL10 or XCOR engine. But you've got the trade space right, number of engines and vehicle length.

I am curious about the versatility of the ACES stage, is it foreseen to be used with any other current, planned and/or future boost stages?

The plan is for ACES to replace Centaur. In the past we had looked at ACES on DIV (ACES in DIV heavy is a great heavy lifter...). But with our plans to retire DIV, Vulcan will be the sole user of ACES.

I watched the presentation and one thing struck me about upper stage being proposed. Didn't the original ACES paper have them switching from the current Centaur Stainless tank to a larger Al-Li tank. Tory made it quite clear the new upper stage being proposed will use new Stainless tanking.

Care to elaborate on the ACES's switch from the new tank using Al-Li to Stainless? Why is it superior? Better mass fraction? Easier to make? Cheaper to make? 70 years of experience manufacturing balloon tanks with Stainless?

I am just curious why it is superior for the new upper stage.

Thanks.

We've studied different upperstage structural designs for decades and have yet to find anything better that stainless in terms of mass fraction and cost. For example, several years ago we got some technology money from NASA to look at friction stirweld of thin walled aluminum tanks. The technology worked, but the best we could do was match the weight at a higher cost of stainless. For ACES, we are going to modern robotic manufacturing methods to reduce the cost further.

One question per member to ensure Dr. Sowers isn't overloaded with questions. Ensure your question is well presented, readable and worthwhile and please read the coverage of the reveal here: http://forum.nasaspaceflight.com/index.php?topic=37251.0 - to ensure you don't ask a question already addresses (or that you ensure it asked for clarification of an answer).

Before I dive into the questions, I'd like to thank Chris for giving me the opportunity to do this Q&A. As I wrote in a recent op ed (http://dpo.st/1albze6 ) developing new rockets is a good as it gets for someone in our business. It's clear that all of you share my enthusiasm. And that makes answering your questions really fun.

OK, I have to take a break. I'll be back later today. Thanks for the great questions!

Dr. Sowers - What drove the decision to select an as-yet unbuilt and untested engine from a new player in the aerospace world (BE-4 from B.O.)? If ULA were selecting an existing engine with flight heritage (RS-68 for example) it would provide an obvious schedule acceleration benefit. But when considering a new American built engine, especially in the non traditional methalox category, for vertical integration reasons it would seem to make sense for ULA to develop its own.

Removing my second question per request from mods.Did ULA consider using SpaceX engines on its rockets? Raptor will be methalox, and in the right thrust regime for a 2-engine Vulcan first stage. Is this even a feasible business move?

ULA has a long history of successful missions, SpaceX is an emerging business, and Blue Origin an enigma. Overall, it seems that everyone is losing the PR war with the general public -most people just don't care. A number of space enthusiasts are excited for SpaceX's entry into the market, simply because of their grander stated ambitions (realistic or not).

How can/will ULA help reinvigorate the public's appetite for spaceflight?

One question each please, in the interests of fairness. Those of you that have more than one question in your post, please revise down to just one question... thanks!

Logged

"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Thank you for taking the time to discuss the Vulcan rocket plans with us!

I have a question regarding the use of Centaur. All things being equal, it would seem the Centaur (with its balloon tankage and common bulkhead) is a more complicated stage to build, transport and prepare for launch than, say the Delta IV's DCSS (separate tanks). Would a DCSS-derivative not offer a cheaper stage for Vulcan than Centaur?

Concerning the previously announced IVF technology to be used in Vulcan and specifically the ACES, how far along is ULA in developing an internal combustion engine that can run on hydrogen and oxygen and survive the implied temperatures and pressures (plus the vibration regime of a solids-assisted launch), be able to maintain lubrication over weeks and/or months spent quiescent in orbit, etc.?

Dr. Sowers; In the recent past (2010) here on NSF there was a thread which discussed in depth an American equivalent to the Russian Vulcan, to be flown by Energya. http://www.k26.com/buran/info/hercules/vulkan.html. That potential LV system was called AJAX http://forum.nasaspaceflight.com/index.php?topic=22266.msg618244#msg618244 and used varying numbers of Atlas CCB’s as LRB’s to cover a wide range of lift requirements ranging from 70 tonnes to 280 tonnes to LEO, from 2 LRB’s up to 8 LRB’s. It even specifically called for the use of ULA's ACES upper stage. The 3 most difficult engineering problems were the flexible locations of the LRB interfaces, avionics with the ability to manage variable numbers of LRB’s and the structural integrity of any upper stage imposing limiting factors on the usable lift capacity. None of these engineering conditions are too difficult to address so I looked at the potential of ULA's new Vulcan potentially filling that role. What was revealed yesterday was a single core with varying numbers of SRB’s, but I noticed that the central core could just as easily accommodate 2, 4 or even 6 additional Vulcan cores in the role of LRB’s. Such a vehicle would offer the United States, indeed the entire world, the ability to have a single LV family capable of covering Medium, Heavy and Super Heavy lift capabilities, without the expense of designing, building and flying many different vehicles, by simply varying the LRB count. So my question would be do you believe it would be a smart business move to design the Vulcan in such a way that does not preclude the on-demand ability to satisfy the less common needs of a Heavy or even a Super Heavy launch? Even though such large lift requirements would not be the norm, just knowing there was a vehicle available to handle it would likely free DoD and NASA mission planners to make use of the capacity.

Dr. Sowers, Thank you for your invaluable insight and for giving us the opportunity to interact with the pros of the industry.I'm wondering about the Vulcan's core tank tooling. I'm assuming you'll be re purposing the Delta IV LOX tank tooling. But I also saw that you are trying to get it to be manufacturable, and Delta IV is not exactly know for that. So, are you going to basically put two appropriately sized DIV LOX tanks on top of the other with an intertank and an external down comer, or are you going to add improvements like internal down comer, common bulkhead and improved alloys (like Al 2195 or Al 2050), etc.? Can you elaborate on some of the improvements?

The timeline that was given in the presentation predicts three events for 2019 being - Vulcan flight no1, Delta IV retire, Atlas V ban validation.It was also noted that Vulcan will only be certified ~3 years later.That leaves 3 years in which ULA will have only one legal alternative for all USAF payloads which is DIVH.Assuming the law won't change, I would like to know how ULA is addressing this apparent problem.

Dr Sowers, What vehicle configuration naming system are you going to employ on Vulcan since you will now need a fourth number to distinguish the change now between the Centaur US and ACES US; and would that naming system have to be altered to account for any additional stages the customer selects such as Castor 30 and/or Star-37FM??

This is my first post on the forum but I suppose it's a good way to start by asking a question.

Since Vulcan is a medium-heavy class vehicle, there will be a void left by the retirement of Delta II. What is the reasoning behind not replacing Delta II?1) ULA cedes Delta II-class payload to other launch service providers to concentrate on EELV-class payload or2) Future payload will all exceed Delta II's capabilities or3) Vulcan will still be used for small payload through dual/multi-launching like Ariane 5.